Amorphous La2Hf2O7 thin films were deposited on Si(100) substrate by pulsed laser deposition (PLD) method under different conditions.The interfacial states of the La2Hf2O7/Si films were studied by synchrotron X-ray reflectivity (XRR) and X-ray photoelectron spec-troscopy (XPS).When grown under vacuum condition,silicate,silicide and few SiOx were formed in the interface layer.However,the Hf-silicide formation could be effectively eliminated by the ambient oxygen pressure during film growth.The result revealed that the La2Hf2O7/Si interlayer was intimately related with growth condition.Insufficient supply of oxygen would cause Hf-silicide formation at the interface and it could be most effectively controlled by the ambient oxygen pressure during film growth.